Starting system for free piston units



KJC- COOPER STARTING SYSTEM FOR FREE PISTON UNITS Nov. 9,1 1948,

Filed Jan. 28, 1944 2 Sheets-Sheet 1 CZ WW ATTORNEY Nov. 9, 1948. K, OPQ 2,453,495

STARTING SYSTEM FOR FREE PISTQN UNITS Filed Jan. 28, 1944 l-NVENTQR 'Mfl W GZAWM ATTORNEY 2 Sheets-Sheet 2 I Patented Nov. 9, 1948 Kenneth 6. Cooper, Portland, Conm, assignor to United Aircraft Corporation, East Hartford, Conn.r acorporation of Delaware Application January 28, 1944, Serial No. 520,072

Claims.

This invention relates to an accumulator device particularly adapted for controlling the admission of gas to a freepiston engine-and-compressor unit for starting. In certain respectsthe inven tion is. a modification of that described in the copending application of Cooper, Serial No. 495,926, filed July 23, 1943, now Patent No.

2,441,186, dated 11, 19418;.

In the above application the accinnulator valve is controlled by a piston connected to the valve and moving in a cylinder to one end of which gas under" pressure is admitted for holding the valve closed. Venting oi thecylinder permits the valve to open. A feature of this invention is the admission of a positive pressure to the cylinder for causing the valve to open rathe'r'than using a drop in pressure for this purpose. Another feature of the invention is a valve structure in which the valve is held closed bymessure on the control piston applied directly to the piston from the accumulator chamber and the valve is caused to open by applying the same pressure to the other-side of. the' piston.

Other objects and advantages will be apparent from the specification and claims, and from the i accompanying drawings which illustrate an embodimentof the invention. r

Fig. l is a sectional View through; a free-piston unit incorporating the starting device. Fig. 2 is a diagrammatic view of the starting system.

Fig. 3 is a sectional view on line 3-3 of Fig. 2. The unit shown, includes an. enginecyl nder in having reciprocating pistons l2 and M to whi'h compressor pistons 16 and la in. cylinders 20 and are integrally connected. Sleeves 24 and 26 attached to the pistons complete the reciprocating piston assemblies, The sleeves incom-bina tion with. stationary pistons 28 and 30 form. air spring cylinders.

The piston assemblies are moved apart by the burning of fuel injected into engine cylinder [has by a. device 32.. Air compressed in the airspring cylinders on the-power stroke returns the piston assemblies The assemblies are always maintained. at equal distances from the center of the engine cylinder by a linkage, which may include racks 34 extending from the compressor pistons. I'ntakemanitold 3'8 conducts air to intakevalves 411 through. which air alternately enters opposite ends oi the compressor. cylinders The com.- pressed air leaves the cylinders throughdischarge valves 42; also. at opposite ends of the compressor cylinders and passes through scavenge, manifold Al through ports 48 and 48: are. uncovered 2 bypistons I2 and M at the end of the power stroke thereby permitting air. to be blown through the engine cylinder and exhaust ports 5i! and '52 into exhaust manifold 54.

Starting devices 56' and 53 for the unit are mounted in air spring pistons 28 and 30. The devices are similar and device 58 will be described in detail. Piston 30 forms a housing held within the unit by a threaded ring 60 and having an accumulater chamber 62 in which gas under pressure is collected in readiness for starting. This chamber communicates with the air spring cylinder through a port 64' closed by a'p-oppet valve 65. The stern-6'8 of this valve is slidable in a guide on a cap 12 which closes the end of chamber 52. Valve 66 closes port M by movement toward the storage chamber and is opened by movement away from the chamber so that pressure of gas within the chamber opens the valve. Pressure of gas in the air spring tends to hold the valve closed during o eration of the unit.

Cap 12 has a bore forming a cyl nder M which receives a piston 16 on the. end of valve stem 68. The inner end of cylinder-l4 is connected withthe storage chamber by one or more ports 18.. A coil spring in the cylind'er moves the piston toward valve closing position. A. head 82 closes the outer end of cylinder l4- and is held in: position by studs 8d extending through both head 82 and cap 12.

A casing 86 on head 82 has a bore 88 in which a plunger 9!! is slidable. One end of bore 88 is in a position to cut oil fluid connection. between passages 98 and se ame has a groove lei! which, when the plunger is moved to the opposite end of its stroke, as limited by the pin! i! i, connects these passages and permits gas to flow through channel 89 into the outer end of cylinder M, to cause valve 66. to open.

For moving plunger 90 to the. inner end of its stroke, casing 86'has a gas inlet passage 182 which is connected by a groan/e103 in plateBZ to the outer end of bore 38. When gas under pressure enters this inlet passage,.;it movesplunger 90 into a; position to close channel. 96' and to connect passages 98 and 99 to establish fluid connection between chamber 62 and the outer end of cylinder I4. When this occurs, the pressures on opposite sides of piston I6 are balanced and the pressure on valve 66 opens the valve for the escape of gas into the air spring. e

In starting the unit, gas under pressure is first admitted through channel 94 until a predetermined pressure is built up in chamber 62. After this pressure is reached, gas under pressure is admitted through channel I02 thereby moving plunger 90 to close passage 96 and to cause valve 68 to open. Before this action occurs, the piston assemblies of the unit will have been moved to starting position. The sudden inrush of air into the air springs from chambers 62 in starting devices 56 and 58 will move the piston assemblies rapidly toward each other.

The starting devices 56 and 58 may be con trolled by an automatically operating valve I04 which controls the admission of gas under pressure to channel 94 and passage I02. Valve I04 includes a casing I06 having a bore in which a valve plunger I08 is mounted, the plunger being normally held in the position shown by a spring H0. The tension of spring IIO may be adjusted by a nut II2 engaging threads in casing I06 to control the pressure in chamber 62 at which the starting device operates.

Casing I06 has an inlet port II4 connected to a source of gas under pressure, and an outlet port II6 connected by'a conduit H8 to channel 94. Another outlet port I spaced from port H6 is connected by a conduit I22 to passage I02. In

' the normal position of plunger I08 a groove I24 in the plunger connects ports I I4 and IIS and another groove I26 connects port I20 to the end of casing I06. When plunger I08 is shifted to the other end of its stroke, as limited by a threaded ring I28, groove I24 connects inlet port II4 with port I20, and another groove I30 connects port I I6 to a vent port I32.

For moving plunger I08, the end of casing I06 has a nut I33 with a through passage I34. Nut I33 clamps a bushing I35, the end of which forms a valve seat engaged by the end of plunger I08. Passage I34 is connected by a branch conduit I36 to conduit I38 which connectswith inlet port II 4. Branch conduit I36 has an adjustable throttle valve I40 which provides a restriction greater than any restriction from'conduit I38 to the chamber 62. When the desired pressure is developed in chamber 62, the pressure in passage I34 acting on the end of plunger I08 moves the plunger against the action of spring IIO to connect port I20 to inlet port I I4 for procuring ope ing of valve 66 for starting the unit.

A small bleed passage I 42 in casing I06 provides fluid connection from the end of plunger I08 to groove I30 which connects with vent port I32. This permits gas leaking past the end of plunger I08 to be vented so that the plunger will not be moved from the position shown until the desired pressure has been built up in chamber 62.

A passage I44 in casing 86 connects passage 90 with groove I03 in cap 92 and is closed by a check valve I46. After the starting unit has operated and conduit I22 is vented by plunger I08 returning to the position shown, gas at the right of piston 16 in cylinder I4 may escape past valve I46 so that piston 16 may move into a position for closing poppet valve 66.

It is understood that the invention is not limited to the specific embodiment herein illustrated and described, but may be used in other ways without 4 departure from its spirit as defined by the following claims.

I claim:

1. In an accumulator device, a housing having a storage chamber and an outlet port for the chamber, a valve closing the port and movable to open position by pressure in the chamber acting on said valve, a piston and cylinder one of which is connected to said valve, inlet means for admitting fluid under pressure to said chamber, a connection from said chamber to the cylinder at one side of the piston for admitting pressure to the cylinder to hold the valve closed, and means for admitting fluid under pressure to the other end of said cylinder for causing the valve to open and for simultaneously closing said inlet means.

2. In a valve structure for the rapid delivery of a measured quantity of compressed fluid to a chamber, a housing having a storage chamber therein mounted adjacent to said first chamber and having an outlet port providing communication between said chambers, a valve closing said port and movable by pressure in said storage chamber in a direction for opening the port, a piston and cylinder, one of Which is connected to the valve, means for admitting fluid under pressure for said storage chamber to one end of the cylinder for holding the valve closed, and inlet means for introducing fluid under. pressure to said storage chamber, in combination with means for introducing fluid under pressure to the other end of said cylinder for causing the valve to open and for simultaneously closing said inlet means.

3. In a valve structure for the rap-id delivery of a measured quantity of compressed fluid to a chamber, a housing having a storage chamber therein mounted adjacent to said'flrst chamber and having an outlet port providing communication between said chambers, a valve closing said port and movable by pressure in said storage chamber in a direction for opening the port, a piston and cylinder, one of which is connected to the valve, means for admitting fluid under pressure from said storage chamber to one end of the cylinder for holding the valve closed, and inlet means for introducing fluid under pressure to said storage chamber, in combination with means for introducing fluid from said storage chamber to the other end of said c linder for balancing the pressures on the piston and causing the valve to open and for simultaneously closing said inlet means.

4. In a valve structure for the rapid delivery of a measured quantity of compressed fluid to a chamber, a housing having a storage chamber therein mounted adjacent to said first chamber and having an outlet port providing communication between said chambers, a valve closing said port and movable by pressure in said storage chamber in a direction for opening the port, a piston and cylinder one of which is connected to the valve, means for admitting fluid under presof a measured quantity of compressed fluid to a chamber, a'housing having a storage chamber therein mounted adjacent to said first chamber and having a port providing communication between said chambers, a Valve closing said port and movable by pressure in said storage chamber in a direction for opening the port, a piston and cylinder one of which is connected to the valve, means for admitting fluid under pressure from said storage chamber to one end of the cylinder for holding the valve closed, a fluid inlet to the chamber and means automatically operative when the pressure in said storage chamber reaches a predetermined value for admitting fluid from said storage chamber to the other side of the piston for causing the valve to open and for simultaneously closing the fluid inlet.

6. In a valve structure for the rapid delivery of a measured quantity of compressed fluid to a chamber, a housing, having a storage chamber therein mounted adjacent to said first chamber and having a port providing communication between said chambers, a valve closing said port and movable by pressure in said storage chamber in a direction for opening the port, a piston and cylinder one of which is connected to the valve, means for admitting fluid under pressure from said storage chamber to one end of the cylinder for holding the valve closed, a fluid inlet to the chamber, a valve movable by fluid pressure for closing the fluid inlet and for admitting fluid from said storage chamber to the other side of the piston for causing the port closing valve to open.

"7. In a valve structure for the rapid delivery of a measured quantity of compressed fluid to. a chamber, a housing having a storage chamber therein mounted adjacent to said first chamber and having a port providing communication between said chambers, a valve closing said port and movable by pressure in said storage chamber in a direction for opening the port, a piston and cylinder one of which is connected to the valve, means for admitting fluid under pressure from said storage chamber to one end of the cylinder for holding the valve closed, a fluid inlet to the chamber, a plunger valve movable by fluid under pressure for closing the fluid inlet and for simultaneously admitting fluid from said storage chamber to the other side of the piston and a pressure responsive valve for admitting fluid under pressure to the end of said plunger valve for actuating it at a pre-determined point in the operation of the structure,

8. In an accumulator device, a housing having a storage chamber and an outlet port for the chamber, a valve closing the port, a cylinder and a piston, one of which is connected to said valve, means for introducing fluid under pressure to one end of said cylinder for holding the valve closed, an inlet to said chamber, means for closing said inlet, and means associated with said inlet closing means for introducing fluid under pressure to the other end of the cylinder simultaneously with the closing of said inlet, the introduction of fluid to said other end of the cylinder operating for balancing the pressures on the piston to cause the valve to open.

9. In an accumulator device, a housing having a storage chamberand an outlet port for the chamber, a valve closing the port, a piston connected to said valve, said housing having a bore in which the piston is slidable, inlet means for admitting fluid to said chamber, means for closing said inlet means, said housing having a passage for admitting fluid from the chamber to the said bore at one side of the piston for holding the valve closed, and means associated with said inlet closing means for admitting gas under pressure to the opposite side of the piston for causing the valve to open simultaneously with the closing of said inlet means.

10. In an accumulator device, a housing having a storage chamber and an outlet port for the chamber, a valve closing the port, a piston connected to said valve, said housing having a bore in which the piston is slidable, inlet means for admitting fluid to said chamber, means for closing said inlet means, said housing having a passage for admitting fluid from the chamber to the said bore at one side of the piston for holding the valve closed, and means associated with said inlet closing means for admitting gas under pressure to the opposite side of the piston simultaneously with the closing of said inlet, the introduction of fluid to said other end of the cylinder operating to balance the pressures on the piston for causing the valve to open.

KENNETH C. COOPER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 798,551 Willits Aug. 29, 1905 1,884,179 Parks Oct. :25, 1932 1,918,340 Knaak July 18, 1933 2,215,326 Janicke Sept. 17, 1940 Certificate of Correction Patent No. 2,453,495. November 9, 1948.

KENNETH C. COOPER It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows:

Column 4, line 27, claim 2, for the words for said read from said;

and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Oflice.

Signed and sealed this 1st day of March, A. D. 1949.

THOMAS F. MURPHY,

Assistant (Jommissz'oner of Patents. 

